THE PRESENT INVENTION relates to a safety-belt arrangement and more particularly relates to a safety-belt arrangement adapted for use in a motor vehicle, such as a motor car. The invention also relates to an anchoring unit for use with a safety-belt.
It is desirable to provide a safety-belt arrangement for use in a motor car which can be easily mounted in the car during fabrication of the car.
It is desirable to provide a safety-belt arrangement which can apply a tension to a safety-belt in the event that an accident should occur, so that the occupant of a seat, wearing the safety-belt, is retained firmly in the seat by the safety-belt.
It is desirable to provide a safety-belt arrangement in which when a very substantial force is applied to the safety-belt, for example when the safety-belt is decelerating, a passenger of substantial mass during an accident where a vehicle is undergoing substantial deceleration, the safety-belt should xe2x80x9cyieldxe2x80x9d whilst providing a force-limiting effect.
The present invention seeks to provide an improved safety-belt arrangement.
According to one aspect of this invention there is provided a safety-belt arrangement for use in a motor vehicle, the arrangement comprising a safety-belt, the safety-belt carrying a tongue to co-operate with a buckle, the safety-belt carrying an end fixing, the arrangement further incorporating an anchoring unit incorporating rotatable spool, the spool being provided with a first catch to engage and retain said end fixing fast with the spool in response to a predetermined movement of the end fixing relative to the spool, means being provided to rotate the spool.
Preferably the first catch comprises a spring biased catch adapted to engage and retain the end fixing.
Conveniently the spool defines a passage into which the end fixing maybe inserted, the first catch comprising a spring biased element biased initially to a position extending part way across the passage, the element being adapted to be retracted, from the initial position, by engagement with the end fixing when the end fixing is inserted in to the passage and then, when the end fixing has been fully inserted in to the passage, being adapted to move back to the initial position to engage and retain the end fixing fast with the spool.
Preferably the means provided to rotate the spool are adapted to impart a rotational bias to the spool, and wherein a securing catch is provided to retain the spool in position, the securing catch being movable to a release position in response to the end fixing being moved to a position in which it is fixed fast with the spool, the spool thus rotating to wind in a length of safety-belt.
Advantageously means are provided to limit the degree of rotation that can be effected by the spool under said rotational bias.
Conveniently limiting means comprise a helical formation provided on the spool, and a follower adapted to follow the helical formation whilst moving in a transversely extending guide, the helical formation terminating in a stop engageable by the follower to prevent further rotation of the spool.
Preferably the spool is associated with means which enable the spool to rotate, in response to the application of a substantial force to the safety-belt after the end fixing has been connected to the spool to pay out safety-belt, with a force limiting effect.
Conveniently the means which enable the spool to rotate to pay out safety-belt with a force limiting effect comprise a torsion bar connected to said spool, rotation of the spool causing torsion to be applied to the torsion bar.
Preferably part of the torsion bar is connected to the spool and part is connected to a rotatable element that can rotate in one sense relative to a framework supporting that spool, but which is prevented from rotating in the opposite sense.
Advantageously said rotatable element comprises an end plate associated with the spool, said end plate carrying a toothed catch biased outwardly to engage corresponding teeth and intermediate recesses formed in the periphery of an aperture defined by the said framework.
Preferably the means provided to rotate the spool are adapted to pre-tension the safety-belt, said means being actuable in response to a parameter exceeding a predetermined threshold.
Conveniently the means adapted to rotate the spool are connected to the spool by means of a force limiting element.
Preferably the force limiting element is a torsion bar.
In a preferred embodiment a single torsion bar is provided, torsion being applied to one part of the torsion bar on the paying-out of safety-belt, and another portion of the torsion bar providing the force limiting effect.
Preferably a pillar loop fixing is provided on the safety-belt.
According to another aspect of this invention there is provided an anchoring unit adapted to anchor one end of a safety-belt, provided with an end fixing, the anchoring unit comprising means adapted to receive said end fixing, means adapted to wind in a predetermined length of safety-belt in response to the end fixing being received within said means in the anchoring unit, and means to pay out at least some of the wound-in length of safety-belt, against a resistive force, if the safety-belt is exposed to a force in excess of a predetermined threshold.
Preferably the means to wind in the safety-belt comprises a resiliently biased spool, the spool being provided with a catch adapted to retain the spool in a predetermined position until the end fixing on the safety-belt is connected to the spool, the end fixing being adapted to release the catch to permit rotation of the spool under the applied spring bias.
Conveniently means are provided to limit the degree of rotation that can be effected by the spool under the spring bias.
Advantageously said limiting means comprise a helical formation provided on the spool, and a follower adapted to follow the helical formation whilst moving in a transversely extending guide, the helical formation terminating in a stop engageable by the follower to prevent further rotation of the spool.
Conveniently the resistive force is provided by a torsion bar, said paying-out of safety-belt causing torsion to be applied to the torsion bar.
Preferably one part of the torsion bar is connected to the spool, and another part of the torsion bar is connected to an element that can rotate in one sense relative to a framework supporting the spool, but which is prevented from rotating in the opposite sense.
In one embodiment said element comprises an end plate associated with the spool, said end plate carrying a toothed catch biased outwardly to engage corresponding teeth and intermediate recesses formed in the periphery of an aperture defined by the said framework.
Preferably means are provided to pre-tension said safety-belt.
Conveniently the means to pre-tension the safety-belt comprise means to rotate said spool, said means comprising a torsion bar having part connected to the spool, and having part connected to a drive wheel driven by a pyrotechnic charge.
Advantageously a single torsion bar is provided, one part of the torsion bar providing said resistive force, and another part of the torsion bar extending between the spool and the drive wheel.
In the arrangement the spool may be associated with means adapted to rotate the spool in order to pre-tension the safety-belt, the means to rotate the spool comprising a torsion bar, one part of the torsion bar being connected to the spool, and another part of the torsion bar being connected to a drive wheel adapted to be driven by a pyrotechnic arrangement.
Advantageously means are provided to permit said spool to rotate in one sense, but to prevent rotation of the spool in the opposite sense.
In one embodiment said means to permit rotation of the spool in one sense comprise an element associated with the spool, said element carrying a spring biased catch, the catch being adapted to co-operate with teeth formed on the framework supporting the spool.
Conveniently the torsion bar incorporates a further section adapted to provide a resistive force whilst permitting the paying-out of some of a length of safety-belt wound round the spool, if the safety-belt is exposed to a force in excess of a predetermined threshold.